Here, the values of thecollege_codecolumn must be unique. SQL UNIQUE Constraint Syntax The syntax of the SQLUNIQUEconstraint is: CREATETABLEtable_name ( column_name data_typeUNIQUE); Here, table_nameis the name of the table to be created column_nameis the name of the column where the con...
Databricks SQL Databricks Runtime 將資訊主鍵或資訊外鍵新增為CREATE TABLE或CREATE MATERIALIZED VIEW語句的一部分。 若要將檢查條件約束新增至 Delta Lake 數據表,請在建立數據表之後使用ALTER TABLE。 語法 使用table_constraint子句來定義跨越多個數據行的條件約束,或將語法與數據行定義分開。
The syntax of the SQLCHECKconstraint is: CREATETABLEtable_name ( column_name data_typeCHECK(condition) ); Here, table_nameis the name of the table to be created column_nameis the name of the column where the constraint is to be implemented data_typeis the data type of the column such ...
1. No Action: This is the default behaviour. No Action specifies that if an attempt is made to delete or update a row with a key referenced by foreign keys in existing rows in other tables, an error is raised and the DELETE or UPDATE is rolled back. 2. Cascade: Specifies that if an...
SQL Server / Oracle / MS Access: CREATETABLEPersons ( ID intNOTNULL, LastName varchar(255)NOTNULL, FirstName varchar(255), Age intCHECK(Age>=18) ); To allow naming of aCHECKconstraint, and for defining aCHECKconstraint on multiple columns, use the following SQL syntax: ...
To create aUNIQUEconstraint on the "ID" column when the table is already created, use the following SQL: MySQL / SQL Server / Oracle / MS Access: ALTERTABLEPersons ADDUNIQUE(ID); To name aUNIQUEconstraint, and to define aUNIQUEconstraint on multiple columns, use the following SQL syntax:...
To allow naming of a UNIQUE constraint, and for defining a UNIQUE constraint on multiple columns, use the following SQL syntax: MySQL / SQL Server / Oracle / MS Access: CREATETABLEPersons ( P_IdintNOTNULL, LastNamevarchar(255)NOTNULL, ...
When defining referential integrity from a SQL DDL statement it is necessary to name a constraint when using the CONSTRAINT keyword. If a constraint name is not desired, then do not use the CONSTRAINT keyword. An example of this error would be: CREATE TABLE Customers (CLstNm TEXT(50), CFrs...
Transact-SQL syntax conventions Syntax syntaxsqlคัดลอก [CONSTRAINTconstraint_name] { [NULL|NOTNULL] {PRIMARYKEY|UNIQUE} [CLUSTERED|NONCLUSTERED] [WITHFILLFACTOR= fillfactor ] [WITH(index_option[, ...n ] ) ] [ON{partition_scheme_name(partition_column_name) | filegroup |"default...
Í þessari grein Syntax Arguments Remarks Examples Next steps Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Warehouse in Microsoft FabricSpecifies the properties of a PRIMARY KEY, UNIQUE, FOREIGN KEY, a CHECK constraint, or a DEFAULT definition added to a table ...